From 924e95c6e801937e890178741fc286a86090df33 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Th=C3=A9o=20DELRIEU?= <theo.delrieu@tanker.io>
Date: Wed, 5 Sep 2018 16:42:55 +0200
Subject: [PATCH] refactor is_compatible_string_type

---
 include/nlohmann/detail/meta/type_traits.hpp | 22 +++++++++-----------
 single_include/nlohmann/json.hpp             | 22 +++++++++-----------
 2 files changed, 20 insertions(+), 24 deletions(-)

diff --git a/include/nlohmann/detail/meta/type_traits.hpp b/include/nlohmann/detail/meta/type_traits.hpp
index 1714a3d6..d993bc17 100644
--- a/include/nlohmann/detail/meta/type_traits.hpp
+++ b/include/nlohmann/detail/meta/type_traits.hpp
@@ -90,25 +90,23 @@ template <typename BasicJsonType, typename CompatibleObjectType>
 struct is_compatible_object_type
     : is_compatible_object_type_impl<BasicJsonType, CompatibleObjectType> {};
 
-template<bool B, class RealType, class CompatibleStringType>
+template <typename BasicJsonType, typename CompatibleStringType,
+          typename = void>
 struct is_compatible_string_type_impl : std::false_type {};
 
-template<class RealType, class CompatibleStringType>
-struct is_compatible_string_type_impl<true, RealType, CompatibleStringType>
+template <typename BasicJsonType, typename CompatibleStringType>
+struct is_compatible_string_type_impl <
+    BasicJsonType, CompatibleStringType,
+    enable_if_t<is_detected_exact<typename BasicJsonType::string_t::value_type,
+    value_type_t, CompatibleStringType>::value >>
 {
     static constexpr auto value =
-        std::is_same<typename RealType::value_type, typename CompatibleStringType::value_type>::value and
-        std::is_constructible<RealType, CompatibleStringType>::value;
+        std::is_constructible<typename BasicJsonType::string_t, CompatibleStringType>::value;
 };
 
-template<class BasicJsonType, class CompatibleStringType>
+template <typename BasicJsonType, typename CompatibleStringType>
 struct is_compatible_string_type
-{
-    static auto constexpr value = is_compatible_string_type_impl <
-                                  conjunction<negation<std::is_same<void, CompatibleStringType>>,
-                                  is_detected<value_type_t, CompatibleStringType>>::value,
-                                  typename BasicJsonType::string_t, CompatibleStringType >::value;
-};
+    : is_compatible_string_type_impl<BasicJsonType, CompatibleStringType> {};
 
 template<typename BasicJsonType, typename T>
 struct is_basic_json_nested_type
diff --git a/single_include/nlohmann/json.hpp b/single_include/nlohmann/json.hpp
index cfadee2d..ce08aab8 100644
--- a/single_include/nlohmann/json.hpp
+++ b/single_include/nlohmann/json.hpp
@@ -470,25 +470,23 @@ template <typename BasicJsonType, typename CompatibleObjectType>
 struct is_compatible_object_type
     : is_compatible_object_type_impl<BasicJsonType, CompatibleObjectType> {};
 
-template<bool B, class RealType, class CompatibleStringType>
+template <typename BasicJsonType, typename CompatibleStringType,
+          typename = void>
 struct is_compatible_string_type_impl : std::false_type {};
 
-template<class RealType, class CompatibleStringType>
-struct is_compatible_string_type_impl<true, RealType, CompatibleStringType>
+template <typename BasicJsonType, typename CompatibleStringType>
+struct is_compatible_string_type_impl <
+    BasicJsonType, CompatibleStringType,
+    enable_if_t<is_detected_exact<typename BasicJsonType::string_t::value_type,
+    value_type_t, CompatibleStringType>::value >>
 {
     static constexpr auto value =
-        std::is_same<typename RealType::value_type, typename CompatibleStringType::value_type>::value and
-        std::is_constructible<RealType, CompatibleStringType>::value;
+        std::is_constructible<typename BasicJsonType::string_t, CompatibleStringType>::value;
 };
 
-template<class BasicJsonType, class CompatibleStringType>
+template <typename BasicJsonType, typename CompatibleStringType>
 struct is_compatible_string_type
-{
-    static auto constexpr value = is_compatible_string_type_impl <
-                                  conjunction<negation<std::is_same<void, CompatibleStringType>>,
-                                  is_detected<value_type_t, CompatibleStringType>>::value,
-                                  typename BasicJsonType::string_t, CompatibleStringType >::value;
-};
+    : is_compatible_string_type_impl<BasicJsonType, CompatibleStringType> {};
 
 template<typename BasicJsonType, typename T>
 struct is_basic_json_nested_type